v2.6.22.24-op1
[linux-2.6.22.y-op.git] / kernel / kprobes.c
blob9e47d8c493f3a7638d06892b2835ad87c859f7bf
1 /*
2 * Kernel Probes (KProbes)
3 * kernel/kprobes.c
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19 * Copyright (C) IBM Corporation, 2002, 2004
21 * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
22 * Probes initial implementation (includes suggestions from
23 * Rusty Russell).
24 * 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
25 * hlists and exceptions notifier as suggested by Andi Kleen.
26 * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
27 * interface to access function arguments.
28 * 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
29 * exceptions notifier to be first on the priority list.
30 * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
31 * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
32 * <prasanna@in.ibm.com> added function-return probes.
34 #include <linux/kprobes.h>
35 #include <linux/hash.h>
36 #include <linux/init.h>
37 #include <linux/slab.h>
38 #include <linux/stddef.h>
39 #include <linux/module.h>
40 #include <linux/moduleloader.h>
41 #include <linux/kallsyms.h>
42 #include <linux/freezer.h>
43 #include <linux/seq_file.h>
44 #include <linux/debugfs.h>
45 #include <linux/kdebug.h>
47 #include <asm-generic/sections.h>
48 #include <asm/cacheflush.h>
49 #include <asm/errno.h>
50 #include <asm/uaccess.h>
52 #define KPROBE_HASH_BITS 6
53 #define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
57 * Some oddball architectures like 64bit powerpc have function descriptors
58 * so this must be overridable.
60 #ifndef kprobe_lookup_name
61 #define kprobe_lookup_name(name, addr) \
62 addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
63 #endif
65 static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
66 static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
67 static atomic_t kprobe_count;
69 /* NOTE: change this value only with kprobe_mutex held */
70 static bool kprobe_enabled;
72 DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */
73 DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */
74 static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
76 static struct notifier_block kprobe_page_fault_nb = {
77 .notifier_call = kprobe_exceptions_notify,
78 .priority = 0x7fffffff /* we need to notified first */
81 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
83 * kprobe->ainsn.insn points to the copy of the instruction to be
84 * single-stepped. x86_64, POWER4 and above have no-exec support and
85 * stepping on the instruction on a vmalloced/kmalloced/data page
86 * is a recipe for disaster
88 #define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
90 struct kprobe_insn_page {
91 struct hlist_node hlist;
92 kprobe_opcode_t *insns; /* Page of instruction slots */
93 char slot_used[INSNS_PER_PAGE];
94 int nused;
95 int ngarbage;
98 enum kprobe_slot_state {
99 SLOT_CLEAN = 0,
100 SLOT_DIRTY = 1,
101 SLOT_USED = 2,
104 static struct hlist_head kprobe_insn_pages;
105 static int kprobe_garbage_slots;
106 static int collect_garbage_slots(void);
108 static int __kprobes check_safety(void)
110 int ret = 0;
111 #if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
112 ret = freeze_processes();
113 if (ret == 0) {
114 struct task_struct *p, *q;
115 do_each_thread(p, q) {
116 if (p != current && p->state == TASK_RUNNING &&
117 p->pid != 0) {
118 printk("Check failed: %s is running\n",p->comm);
119 ret = -1;
120 goto loop_end;
122 } while_each_thread(p, q);
124 loop_end:
125 thaw_processes();
126 #else
127 synchronize_sched();
128 #endif
129 return ret;
133 * get_insn_slot() - Find a slot on an executable page for an instruction.
134 * We allocate an executable page if there's no room on existing ones.
136 kprobe_opcode_t __kprobes *get_insn_slot(void)
138 struct kprobe_insn_page *kip;
139 struct hlist_node *pos;
141 retry:
142 hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
143 if (kip->nused < INSNS_PER_PAGE) {
144 int i;
145 for (i = 0; i < INSNS_PER_PAGE; i++) {
146 if (kip->slot_used[i] == SLOT_CLEAN) {
147 kip->slot_used[i] = SLOT_USED;
148 kip->nused++;
149 return kip->insns + (i * MAX_INSN_SIZE);
152 /* Surprise! No unused slots. Fix kip->nused. */
153 kip->nused = INSNS_PER_PAGE;
157 /* If there are any garbage slots, collect it and try again. */
158 if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
159 goto retry;
161 /* All out of space. Need to allocate a new page. Use slot 0. */
162 kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
163 if (!kip)
164 return NULL;
167 * Use module_alloc so this page is within +/- 2GB of where the
168 * kernel image and loaded module images reside. This is required
169 * so x86_64 can correctly handle the %rip-relative fixups.
171 kip->insns = module_alloc(PAGE_SIZE);
172 if (!kip->insns) {
173 kfree(kip);
174 return NULL;
176 INIT_HLIST_NODE(&kip->hlist);
177 hlist_add_head(&kip->hlist, &kprobe_insn_pages);
178 memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
179 kip->slot_used[0] = SLOT_USED;
180 kip->nused = 1;
181 kip->ngarbage = 0;
182 return kip->insns;
185 /* Return 1 if all garbages are collected, otherwise 0. */
186 static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
188 kip->slot_used[idx] = SLOT_CLEAN;
189 kip->nused--;
190 if (kip->nused == 0) {
192 * Page is no longer in use. Free it unless
193 * it's the last one. We keep the last one
194 * so as not to have to set it up again the
195 * next time somebody inserts a probe.
197 hlist_del(&kip->hlist);
198 if (hlist_empty(&kprobe_insn_pages)) {
199 INIT_HLIST_NODE(&kip->hlist);
200 hlist_add_head(&kip->hlist,
201 &kprobe_insn_pages);
202 } else {
203 module_free(NULL, kip->insns);
204 kfree(kip);
206 return 1;
208 return 0;
211 static int __kprobes collect_garbage_slots(void)
213 struct kprobe_insn_page *kip;
214 struct hlist_node *pos, *next;
216 /* Ensure no-one is preepmted on the garbages */
217 if (check_safety() != 0)
218 return -EAGAIN;
220 hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) {
221 int i;
222 if (kip->ngarbage == 0)
223 continue;
224 kip->ngarbage = 0; /* we will collect all garbages */
225 for (i = 0; i < INSNS_PER_PAGE; i++) {
226 if (kip->slot_used[i] == SLOT_DIRTY &&
227 collect_one_slot(kip, i))
228 break;
231 kprobe_garbage_slots = 0;
232 return 0;
235 void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
237 struct kprobe_insn_page *kip;
238 struct hlist_node *pos;
240 hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
241 if (kip->insns <= slot &&
242 slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
243 int i = (slot - kip->insns) / MAX_INSN_SIZE;
244 if (dirty) {
245 kip->slot_used[i] = SLOT_DIRTY;
246 kip->ngarbage++;
247 } else {
248 collect_one_slot(kip, i);
250 break;
254 if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
255 collect_garbage_slots();
257 #endif
259 /* We have preemption disabled.. so it is safe to use __ versions */
260 static inline void set_kprobe_instance(struct kprobe *kp)
262 __get_cpu_var(kprobe_instance) = kp;
265 static inline void reset_kprobe_instance(void)
267 __get_cpu_var(kprobe_instance) = NULL;
271 * This routine is called either:
272 * - under the kprobe_mutex - during kprobe_[un]register()
273 * OR
274 * - with preemption disabled - from arch/xxx/kernel/kprobes.c
276 struct kprobe __kprobes *get_kprobe(void *addr)
278 struct hlist_head *head;
279 struct hlist_node *node;
280 struct kprobe *p;
282 head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
283 hlist_for_each_entry_rcu(p, node, head, hlist) {
284 if (p->addr == addr)
285 return p;
287 return NULL;
291 * Aggregate handlers for multiple kprobes support - these handlers
292 * take care of invoking the individual kprobe handlers on p->list
294 static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
296 struct kprobe *kp;
298 list_for_each_entry_rcu(kp, &p->list, list) {
299 if (kp->pre_handler) {
300 set_kprobe_instance(kp);
301 if (kp->pre_handler(kp, regs))
302 return 1;
304 reset_kprobe_instance();
306 return 0;
309 static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
310 unsigned long flags)
312 struct kprobe *kp;
314 list_for_each_entry_rcu(kp, &p->list, list) {
315 if (kp->post_handler) {
316 set_kprobe_instance(kp);
317 kp->post_handler(kp, regs, flags);
318 reset_kprobe_instance();
323 static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
324 int trapnr)
326 struct kprobe *cur = __get_cpu_var(kprobe_instance);
329 * if we faulted "during" the execution of a user specified
330 * probe handler, invoke just that probe's fault handler
332 if (cur && cur->fault_handler) {
333 if (cur->fault_handler(cur, regs, trapnr))
334 return 1;
336 return 0;
339 static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
341 struct kprobe *cur = __get_cpu_var(kprobe_instance);
342 int ret = 0;
344 if (cur && cur->break_handler) {
345 if (cur->break_handler(cur, regs))
346 ret = 1;
348 reset_kprobe_instance();
349 return ret;
352 /* Walks the list and increments nmissed count for multiprobe case */
353 void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
355 struct kprobe *kp;
356 if (p->pre_handler != aggr_pre_handler) {
357 p->nmissed++;
358 } else {
359 list_for_each_entry_rcu(kp, &p->list, list)
360 kp->nmissed++;
362 return;
365 /* Called with kretprobe_lock held */
366 void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
367 struct hlist_head *head)
369 /* remove rp inst off the rprobe_inst_table */
370 hlist_del(&ri->hlist);
371 if (ri->rp) {
372 /* remove rp inst off the used list */
373 hlist_del(&ri->uflist);
374 /* put rp inst back onto the free list */
375 INIT_HLIST_NODE(&ri->uflist);
376 hlist_add_head(&ri->uflist, &ri->rp->free_instances);
377 } else
378 /* Unregistering */
379 hlist_add_head(&ri->hlist, head);
382 struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
384 return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
388 * This function is called from finish_task_switch when task tk becomes dead,
389 * so that we can recycle any function-return probe instances associated
390 * with this task. These left over instances represent probed functions
391 * that have been called but will never return.
393 void __kprobes kprobe_flush_task(struct task_struct *tk)
395 struct kretprobe_instance *ri;
396 struct hlist_head *head, empty_rp;
397 struct hlist_node *node, *tmp;
398 unsigned long flags = 0;
400 INIT_HLIST_HEAD(&empty_rp);
401 spin_lock_irqsave(&kretprobe_lock, flags);
402 head = kretprobe_inst_table_head(tk);
403 hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
404 if (ri->task == tk)
405 recycle_rp_inst(ri, &empty_rp);
407 spin_unlock_irqrestore(&kretprobe_lock, flags);
409 hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
410 hlist_del(&ri->hlist);
411 kfree(ri);
415 static inline void free_rp_inst(struct kretprobe *rp)
417 struct kretprobe_instance *ri;
418 struct hlist_node *pos, *next;
420 hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) {
421 hlist_del(&ri->uflist);
422 kfree(ri);
427 * Keep all fields in the kprobe consistent
429 static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
431 memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
432 memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
436 * Add the new probe to old_p->list. Fail if this is the
437 * second jprobe at the address - two jprobes can't coexist
439 static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
441 if (p->break_handler) {
442 if (old_p->break_handler)
443 return -EEXIST;
444 list_add_tail_rcu(&p->list, &old_p->list);
445 old_p->break_handler = aggr_break_handler;
446 } else
447 list_add_rcu(&p->list, &old_p->list);
448 if (p->post_handler && !old_p->post_handler)
449 old_p->post_handler = aggr_post_handler;
450 return 0;
454 * Fill in the required fields of the "manager kprobe". Replace the
455 * earlier kprobe in the hlist with the manager kprobe
457 static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
459 copy_kprobe(p, ap);
460 flush_insn_slot(ap);
461 ap->addr = p->addr;
462 ap->pre_handler = aggr_pre_handler;
463 ap->fault_handler = aggr_fault_handler;
464 if (p->post_handler)
465 ap->post_handler = aggr_post_handler;
466 if (p->break_handler)
467 ap->break_handler = aggr_break_handler;
469 INIT_LIST_HEAD(&ap->list);
470 list_add_rcu(&p->list, &ap->list);
472 hlist_replace_rcu(&p->hlist, &ap->hlist);
476 * This is the second or subsequent kprobe at the address - handle
477 * the intricacies
479 static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
480 struct kprobe *p)
482 int ret = 0;
483 struct kprobe *ap;
485 if (old_p->pre_handler == aggr_pre_handler) {
486 copy_kprobe(old_p, p);
487 ret = add_new_kprobe(old_p, p);
488 } else {
489 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
490 if (!ap)
491 return -ENOMEM;
492 add_aggr_kprobe(ap, old_p);
493 copy_kprobe(ap, p);
494 ret = add_new_kprobe(ap, p);
496 return ret;
499 static int __kprobes in_kprobes_functions(unsigned long addr)
501 if (addr >= (unsigned long)__kprobes_text_start &&
502 addr < (unsigned long)__kprobes_text_end)
503 return -EINVAL;
504 return 0;
507 static int __kprobes __register_kprobe(struct kprobe *p,
508 unsigned long called_from)
510 int ret = 0;
511 struct kprobe *old_p;
512 struct module *probed_mod;
515 * If we have a symbol_name argument look it up,
516 * and add it to the address. That way the addr
517 * field can either be global or relative to a symbol.
519 if (p->symbol_name) {
520 if (p->addr)
521 return -EINVAL;
522 kprobe_lookup_name(p->symbol_name, p->addr);
525 if (!p->addr)
526 return -EINVAL;
527 p->addr = (kprobe_opcode_t *)(((char *)p->addr)+ p->offset);
529 if (!kernel_text_address((unsigned long) p->addr) ||
530 in_kprobes_functions((unsigned long) p->addr))
531 return -EINVAL;
533 p->mod_refcounted = 0;
536 * Check if are we probing a module.
538 probed_mod = module_text_address((unsigned long) p->addr);
539 if (probed_mod) {
540 struct module *calling_mod = module_text_address(called_from);
542 * We must allow modules to probe themself and in this case
543 * avoid incrementing the module refcount, so as to allow
544 * unloading of self probing modules.
546 if (calling_mod && calling_mod != probed_mod) {
547 if (unlikely(!try_module_get(probed_mod)))
548 return -EINVAL;
549 p->mod_refcounted = 1;
550 } else
551 probed_mod = NULL;
554 p->nmissed = 0;
555 mutex_lock(&kprobe_mutex);
556 old_p = get_kprobe(p->addr);
557 if (old_p) {
558 ret = register_aggr_kprobe(old_p, p);
559 if (!ret)
560 atomic_inc(&kprobe_count);
561 goto out;
564 ret = arch_prepare_kprobe(p);
565 if (ret)
566 goto out;
568 INIT_HLIST_NODE(&p->hlist);
569 hlist_add_head_rcu(&p->hlist,
570 &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
572 if (kprobe_enabled) {
573 if (atomic_add_return(1, &kprobe_count) == \
574 (ARCH_INACTIVE_KPROBE_COUNT + 1))
575 register_page_fault_notifier(&kprobe_page_fault_nb);
577 arch_arm_kprobe(p);
579 out:
580 mutex_unlock(&kprobe_mutex);
582 if (ret && probed_mod)
583 module_put(probed_mod);
584 return ret;
587 int __kprobes register_kprobe(struct kprobe *p)
589 return __register_kprobe(p, (unsigned long)__builtin_return_address(0));
592 void __kprobes unregister_kprobe(struct kprobe *p)
594 struct module *mod;
595 struct kprobe *old_p, *list_p;
596 int cleanup_p;
598 mutex_lock(&kprobe_mutex);
599 old_p = get_kprobe(p->addr);
600 if (unlikely(!old_p)) {
601 mutex_unlock(&kprobe_mutex);
602 return;
604 if (p != old_p) {
605 list_for_each_entry_rcu(list_p, &old_p->list, list)
606 if (list_p == p)
607 /* kprobe p is a valid probe */
608 goto valid_p;
609 mutex_unlock(&kprobe_mutex);
610 return;
612 valid_p:
613 if (old_p == p ||
614 (old_p->pre_handler == aggr_pre_handler &&
615 p->list.next == &old_p->list && p->list.prev == &old_p->list)) {
617 * Only probe on the hash list. Disarm only if kprobes are
618 * enabled - otherwise, the breakpoint would already have
619 * been removed. We save on flushing icache.
621 if (kprobe_enabled)
622 arch_disarm_kprobe(p);
623 hlist_del_rcu(&old_p->hlist);
624 cleanup_p = 1;
625 } else {
626 list_del_rcu(&p->list);
627 cleanup_p = 0;
630 mutex_unlock(&kprobe_mutex);
632 synchronize_sched();
633 if (p->mod_refcounted) {
634 mod = module_text_address((unsigned long)p->addr);
635 if (mod)
636 module_put(mod);
639 if (cleanup_p) {
640 if (p != old_p) {
641 list_del_rcu(&p->list);
642 kfree(old_p);
644 arch_remove_kprobe(p);
645 } else {
646 mutex_lock(&kprobe_mutex);
647 if (p->break_handler)
648 old_p->break_handler = NULL;
649 if (p->post_handler){
650 list_for_each_entry_rcu(list_p, &old_p->list, list){
651 if (list_p->post_handler){
652 cleanup_p = 2;
653 break;
656 if (cleanup_p == 0)
657 old_p->post_handler = NULL;
659 mutex_unlock(&kprobe_mutex);
662 /* Call unregister_page_fault_notifier()
663 * if no probes are active
665 mutex_lock(&kprobe_mutex);
666 if (atomic_add_return(-1, &kprobe_count) == \
667 ARCH_INACTIVE_KPROBE_COUNT)
668 unregister_page_fault_notifier(&kprobe_page_fault_nb);
669 mutex_unlock(&kprobe_mutex);
670 return;
673 static struct notifier_block kprobe_exceptions_nb = {
674 .notifier_call = kprobe_exceptions_notify,
675 .priority = 0x7fffffff /* we need to be notified first */
679 int __kprobes register_jprobe(struct jprobe *jp)
681 /* Todo: Verify probepoint is a function entry point */
682 jp->kp.pre_handler = setjmp_pre_handler;
683 jp->kp.break_handler = longjmp_break_handler;
685 return __register_kprobe(&jp->kp,
686 (unsigned long)__builtin_return_address(0));
689 void __kprobes unregister_jprobe(struct jprobe *jp)
691 unregister_kprobe(&jp->kp);
694 #ifdef ARCH_SUPPORTS_KRETPROBES
697 * This kprobe pre_handler is registered with every kretprobe. When probe
698 * hits it will set up the return probe.
700 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
701 struct pt_regs *regs)
703 struct kretprobe *rp = container_of(p, struct kretprobe, kp);
704 unsigned long flags = 0;
706 /*TODO: consider to only swap the RA after the last pre_handler fired */
707 spin_lock_irqsave(&kretprobe_lock, flags);
708 if (!hlist_empty(&rp->free_instances)) {
709 struct kretprobe_instance *ri;
711 ri = hlist_entry(rp->free_instances.first,
712 struct kretprobe_instance, uflist);
713 ri->rp = rp;
714 ri->task = current;
715 arch_prepare_kretprobe(ri, regs);
717 /* XXX(hch): why is there no hlist_move_head? */
718 hlist_del(&ri->uflist);
719 hlist_add_head(&ri->uflist, &ri->rp->used_instances);
720 hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task));
721 } else
722 rp->nmissed++;
723 spin_unlock_irqrestore(&kretprobe_lock, flags);
724 return 0;
727 int __kprobes register_kretprobe(struct kretprobe *rp)
729 int ret = 0;
730 struct kretprobe_instance *inst;
731 int i;
733 rp->kp.pre_handler = pre_handler_kretprobe;
734 rp->kp.post_handler = NULL;
735 rp->kp.fault_handler = NULL;
736 rp->kp.break_handler = NULL;
738 /* Pre-allocate memory for max kretprobe instances */
739 if (rp->maxactive <= 0) {
740 #ifdef CONFIG_PREEMPT
741 rp->maxactive = max(10, 2 * NR_CPUS);
742 #else
743 rp->maxactive = NR_CPUS;
744 #endif
746 INIT_HLIST_HEAD(&rp->used_instances);
747 INIT_HLIST_HEAD(&rp->free_instances);
748 for (i = 0; i < rp->maxactive; i++) {
749 inst = kmalloc(sizeof(struct kretprobe_instance), GFP_KERNEL);
750 if (inst == NULL) {
751 free_rp_inst(rp);
752 return -ENOMEM;
754 INIT_HLIST_NODE(&inst->uflist);
755 hlist_add_head(&inst->uflist, &rp->free_instances);
758 rp->nmissed = 0;
759 /* Establish function entry probe point */
760 if ((ret = __register_kprobe(&rp->kp,
761 (unsigned long)__builtin_return_address(0))) != 0)
762 free_rp_inst(rp);
763 return ret;
766 #else /* ARCH_SUPPORTS_KRETPROBES */
768 int __kprobes register_kretprobe(struct kretprobe *rp)
770 return -ENOSYS;
773 static int __kprobes pre_handler_kretprobe(struct kprobe *p,
774 struct pt_regs *regs)
776 return 0;
779 #endif /* ARCH_SUPPORTS_KRETPROBES */
781 void __kprobes unregister_kretprobe(struct kretprobe *rp)
783 unsigned long flags;
784 struct kretprobe_instance *ri;
785 struct hlist_node *pos, *next;
787 unregister_kprobe(&rp->kp);
789 /* No race here */
790 spin_lock_irqsave(&kretprobe_lock, flags);
791 hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) {
792 ri->rp = NULL;
793 hlist_del(&ri->uflist);
795 spin_unlock_irqrestore(&kretprobe_lock, flags);
796 free_rp_inst(rp);
799 static int __init init_kprobes(void)
801 int i, err = 0;
803 /* FIXME allocate the probe table, currently defined statically */
804 /* initialize all list heads */
805 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
806 INIT_HLIST_HEAD(&kprobe_table[i]);
807 INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
809 atomic_set(&kprobe_count, 0);
811 /* By default, kprobes are enabled */
812 kprobe_enabled = true;
814 err = arch_init_kprobes();
815 if (!err)
816 err = register_die_notifier(&kprobe_exceptions_nb);
818 return err;
821 #ifdef CONFIG_DEBUG_FS
822 static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
823 const char *sym, int offset,char *modname)
825 char *kprobe_type;
827 if (p->pre_handler == pre_handler_kretprobe)
828 kprobe_type = "r";
829 else if (p->pre_handler == setjmp_pre_handler)
830 kprobe_type = "j";
831 else
832 kprobe_type = "k";
833 if (sym)
834 seq_printf(pi, "%p %s %s+0x%x %s\n", p->addr, kprobe_type,
835 sym, offset, (modname ? modname : " "));
836 else
837 seq_printf(pi, "%p %s %p\n", p->addr, kprobe_type, p->addr);
840 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
842 return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
845 static void __kprobes *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
847 (*pos)++;
848 if (*pos >= KPROBE_TABLE_SIZE)
849 return NULL;
850 return pos;
853 static void __kprobes kprobe_seq_stop(struct seq_file *f, void *v)
855 /* Nothing to do */
858 static int __kprobes show_kprobe_addr(struct seq_file *pi, void *v)
860 struct hlist_head *head;
861 struct hlist_node *node;
862 struct kprobe *p, *kp;
863 const char *sym = NULL;
864 unsigned int i = *(loff_t *) v;
865 unsigned long offset = 0;
866 char *modname, namebuf[128];
868 head = &kprobe_table[i];
869 preempt_disable();
870 hlist_for_each_entry_rcu(p, node, head, hlist) {
871 sym = kallsyms_lookup((unsigned long)p->addr, NULL,
872 &offset, &modname, namebuf);
873 if (p->pre_handler == aggr_pre_handler) {
874 list_for_each_entry_rcu(kp, &p->list, list)
875 report_probe(pi, kp, sym, offset, modname);
876 } else
877 report_probe(pi, p, sym, offset, modname);
879 preempt_enable();
880 return 0;
883 static struct seq_operations kprobes_seq_ops = {
884 .start = kprobe_seq_start,
885 .next = kprobe_seq_next,
886 .stop = kprobe_seq_stop,
887 .show = show_kprobe_addr
890 static int __kprobes kprobes_open(struct inode *inode, struct file *filp)
892 return seq_open(filp, &kprobes_seq_ops);
895 static struct file_operations debugfs_kprobes_operations = {
896 .open = kprobes_open,
897 .read = seq_read,
898 .llseek = seq_lseek,
899 .release = seq_release,
902 static void __kprobes enable_all_kprobes(void)
904 struct hlist_head *head;
905 struct hlist_node *node;
906 struct kprobe *p;
907 unsigned int i;
909 mutex_lock(&kprobe_mutex);
911 /* If kprobes are already enabled, just return */
912 if (kprobe_enabled)
913 goto already_enabled;
916 * Re-register the page fault notifier only if there are any
917 * active probes at the time of enabling kprobes globally
919 if (atomic_read(&kprobe_count) > ARCH_INACTIVE_KPROBE_COUNT)
920 register_page_fault_notifier(&kprobe_page_fault_nb);
922 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
923 head = &kprobe_table[i];
924 hlist_for_each_entry_rcu(p, node, head, hlist)
925 arch_arm_kprobe(p);
928 kprobe_enabled = true;
929 printk(KERN_INFO "Kprobes globally enabled\n");
931 already_enabled:
932 mutex_unlock(&kprobe_mutex);
933 return;
936 static void __kprobes disable_all_kprobes(void)
938 struct hlist_head *head;
939 struct hlist_node *node;
940 struct kprobe *p;
941 unsigned int i;
943 mutex_lock(&kprobe_mutex);
945 /* If kprobes are already disabled, just return */
946 if (!kprobe_enabled)
947 goto already_disabled;
949 kprobe_enabled = false;
950 printk(KERN_INFO "Kprobes globally disabled\n");
951 for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
952 head = &kprobe_table[i];
953 hlist_for_each_entry_rcu(p, node, head, hlist) {
954 if (!arch_trampoline_kprobe(p))
955 arch_disarm_kprobe(p);
959 mutex_unlock(&kprobe_mutex);
960 /* Allow all currently running kprobes to complete */
961 synchronize_sched();
963 mutex_lock(&kprobe_mutex);
964 /* Unconditionally unregister the page_fault notifier */
965 unregister_page_fault_notifier(&kprobe_page_fault_nb);
967 already_disabled:
968 mutex_unlock(&kprobe_mutex);
969 return;
973 * XXX: The debugfs bool file interface doesn't allow for callbacks
974 * when the bool state is switched. We can reuse that facility when
975 * available
977 static ssize_t read_enabled_file_bool(struct file *file,
978 char __user *user_buf, size_t count, loff_t *ppos)
980 char buf[3];
982 if (kprobe_enabled)
983 buf[0] = '1';
984 else
985 buf[0] = '0';
986 buf[1] = '\n';
987 buf[2] = 0x00;
988 return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
991 static ssize_t write_enabled_file_bool(struct file *file,
992 const char __user *user_buf, size_t count, loff_t *ppos)
994 char buf[32];
995 int buf_size;
997 buf_size = min(count, (sizeof(buf)-1));
998 if (copy_from_user(buf, user_buf, buf_size))
999 return -EFAULT;
1001 switch (buf[0]) {
1002 case 'y':
1003 case 'Y':
1004 case '1':
1005 enable_all_kprobes();
1006 break;
1007 case 'n':
1008 case 'N':
1009 case '0':
1010 disable_all_kprobes();
1011 break;
1014 return count;
1017 static struct file_operations fops_kp = {
1018 .read = read_enabled_file_bool,
1019 .write = write_enabled_file_bool,
1022 static int __kprobes debugfs_kprobe_init(void)
1024 struct dentry *dir, *file;
1025 unsigned int value = 1;
1027 dir = debugfs_create_dir("kprobes", NULL);
1028 if (!dir)
1029 return -ENOMEM;
1031 file = debugfs_create_file("list", 0444, dir, NULL,
1032 &debugfs_kprobes_operations);
1033 if (!file) {
1034 debugfs_remove(dir);
1035 return -ENOMEM;
1038 file = debugfs_create_file("enabled", 0600, dir,
1039 &value, &fops_kp);
1040 if (!file) {
1041 debugfs_remove(dir);
1042 return -ENOMEM;
1045 return 0;
1048 late_initcall(debugfs_kprobe_init);
1049 #endif /* CONFIG_DEBUG_FS */
1051 module_init(init_kprobes);
1053 EXPORT_SYMBOL_GPL(register_kprobe);
1054 EXPORT_SYMBOL_GPL(unregister_kprobe);
1055 EXPORT_SYMBOL_GPL(register_jprobe);
1056 EXPORT_SYMBOL_GPL(unregister_jprobe);
1057 EXPORT_SYMBOL_GPL(jprobe_return);
1058 EXPORT_SYMBOL_GPL(register_kretprobe);
1059 EXPORT_SYMBOL_GPL(unregister_kretprobe);